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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An automated imaging BRDF polarimeter for fruit quality inspection

Boyer, Jacob, Keresztes, Janos C., Saeys, Wouter, Koshel, John 17 October 2016 (has links)
The purpose of this project was to test and implement recent research of polarization and scatter properties that suggest using a cross polarization imaging system to reduce glare artifacts. In particular, the use of this research is to improve the machine vision of apple quality detection in the food industry. The automated measurement system was implemented by acquiring pictures at different angles and different polarization states of apples. The opto-mechanics, system integration, synchronization and data collection are controlled with LabVIEW.
2

Parametric Opto-Mechanical Performance Analysis of Mounted Lenses Under Thermal Loading

Kadlec, Kal, Kadlec, Kal January 2017 (has links)
Mounting of lenses in opto-mechanical assemblies can create surface figure errors and refractive index changes through thermal and pre-load stresses. As lenses and barrels change in size under temperature changes, the optical performance degrades due to stress and surface deformations. Currently there is no way of determining the effect of these mechanical perturbations on the system wavefront without performing tedious finite element analysis. Most in-depth opto-mechanical analyses involve case-by-case studies with specific designs while previous general studies fail to take into account the complex geometries. The assumptions made by previous general studies ignore the effects of lens shape. These omissions can have a large effect on the stiffness, stress and surface figure error. A parametric model can combine the best of both an in-depth and general study. By parametrizing the model, a simple analysis can be executed for approximating the environmental-mechanical effects on optical performance. This eliminates the time it takes for an opto-mechanical design to be iterated for an optical or mechanical engineer. This tool could be used for early opto-mechanical design or for finite element analysis verification. The parametric model allows the exploration of the broader design study without confining it to a local design space.
3

Improvements to Whole Lens Reconstruction for Saline Submerged Soft Contact Lenses

Guido, Christopher James January 2016 (has links)
A method for measuring the thickness and surface profiles of soft contact lenses while submerged in a saline solution has been implemented utilizing a low coherence Twyman-Green Interferometer. Although the original measurements demonstrated that features on the contact lens surfaces could be accurately determined, it was believed that the layout of the system also induced surface profile distortions. A new opto-mechanical layout has been implemented which eliminates many of these low frequency distortions. Improvements to the original phase unwrapping algorithms have also been developed to overcome the low visibility output inherent to the measurement allowing for a more complete analysis of the two surfaces of a contact lens.

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